As an opening/closing member mounted to a vehicle such as an automobile, there are a back door, a trunk lid, and the like for opening/closing by pivoting and swinging about a hinge and a slide door and the like for opening/closing by moving along a rail.
For example, there are many one-box cars provided with a back door such that baggage can easily be loaded and unloaded from a rear portion of the vehicle. Normally, such a backdoor is mounted through a hinge fixed to a rear end portion of the vehicle body and pivots about the hinge to open and close in a vertical direction. In this case, the back door is also called a flip-up back door because the back door is flipped up high above the vehicle.
Such a back door is flipped up high when opening in many cases to produce a large clearance between an end portion of the back door and the ground and therefore opening and closing of the back door are difficult. Especially for women and children, it is extremely difficult to close such a back door.
Therefore, vehicles mounted with an automatic opening/closing device for enabling women and children to easily open and dose the backdoor are on the increase. Such an automatic opening/closing device includes a pinion driven by a motor which is a driving source and a rack engaged with the pinion, for example, and the rack and the back door are connected by a connecting rod. In automatically opening and closing the back door, power for opening and closing is transferred to the back door through the connecting rod from the rack driven for moving straight by the motor (see Japanese Patent Application Laid-open No. 2001-253241 for example).
However, in mounting the motor, the pinion, and the rack, these parts are fixed to different reference members. By piling a plurality of reference members, the automatic opening/closing device is formed. Because many parts are mounted in this manner, it is difficult to improve accuracy of engagement of the pinion and the rack with each other and such structure may cause wear of engaged faces and generation of engaging sounds. Moreover, reduction in the accuracy of the engagement is undesirable from a viewpoint of power transferring efficiency.
Combination of many parts results not only in increase in cost of the automatic opening/closing device due to increase in the number of parts but also in reduction in vehicle mountability due to fostering of upsizing of the automatic opening/closing device.